Waste of space

Today I have been mostly in London going from one meeting to the other, using rail, tube and feet.

What struck me was the number of advertising boards, both static and video, that were empty. From the first train I got on a board said 'Advertise Here' and it seemed what station I was at there were big empty spaces.

Clearly this is another sign of recession but it's also a waste of space.

There are so many social and environmental messages that could be spread using these empty media channels: poverty, sustainability, biodiversity loss.......

OK designing, printing and putting up posters would incur cost but a number of screens that are controlled remotely and could be filled with simple messages were also blank, advertising nothing but the companies that run the screens.

I realise that these companies have to create revenue but on days like today with so much space left empty surely it could have been put to better use?